With our theme this month being the OMS diet, now is the perfect time to share with you the latest paper from our friends, NEU at the University of Melbourne.
Seasoned ‘OMSers’ may already be aware of the HOLISM Study, but in case you aren’t, or if you are new to the OMS program, it is well worth going over a few of its key findings;
The Health Outcomes and Lifestyles in a Sample of people with Multiple Sclerosis (HOLISM) Study began in 2012, under the leadership of Prof. George Jelinek and involving researchers at the Neuroepidemiology Unit (NEU) of the Melbourne School of Population and Global Health at the University of Melbourne. Collecting and analysing self-reported data from over 2,500 people with MS in 57 countries, they examined a wide range of lifestyle factors and disease outcomes, with some living “healthy lifestyles”, and others that were not. It remains the only independently funded database of modifiable lifestyle risk factors in MS.
To date, they have published more than fifteen papers in international peer-reviewed medical journals looking at the individual risk factors for MS disease progression. Researchers have unpicked the very fine details, for example in diet; uncovering the relative importance of fruit and vegetables, fats, omega-3, fibre and fish consumption on the disease course of MS.
Some of their early headline findings:
60% relapse rate reduction with flaxseed oil supplementation
42% less chance of disability with “healthy fat diet”
33% relapse rate reduction on any vitamin D dose
Significant reduction in risk of depression and fatigue levels
In this most recent HOLISM paper, the team examined the links between diet quality and disease progression. “Higher quality of diet and non-consumption of meat are associated with less disability progression in people with multiple sclerosis” is published in the European Journal of Neurology and is the first study to prospectively examine the relationship between diet quality, disability progression, fatigue and depression risk.
This is vitally important; if we are to change the deeply entrenched views of many clinicians towards diet in MS, we must provide a quality of evidence that is increasingly hard to ignore. A well-conducted prospective cohort study (one where outcomes are assessed during the study period) is generally considered preferrable to retrospective (where information is collected about events that have already occurred) as the risks of bias and confounding factors are less.
Participants from the original HOLISM international cohort were assessed over 2.5 years. Dietary data was obtained using a modified Diet Habits Questionnaire (DHQ), grading diet quality from 1 (poor) to 5 (healthy). Disability was assessed by using the Patient-determined MS Severity Score (P-MSSS), fatigue using the Fatigue Severity Scale, and depression risk using the Patient Health Questionnaire-2. Subjects also reported whether they were experiencing symptoms due to a recent relapse. The researchers then examined the relationships between diet and disease outcomes, both at the beginning of the study, and over the course of the 2.5 year follow-up period, giving the all-important prospective data.
The average age in the group was 48 (range 20 - 81), 82% were female and 18% male, 67% had RRMS and 33% had progressive forms of MS. Among the 1,346 participants, higher DHQ scores (indicating an overall higher quality diet) showed significant associations with lower odds of severe disability, fatigue, and depression risk, cross-sectionally.
Over the 2.5 years, higher baseline DHQ scores were associated with a lower risk of increasing disability, with those in top two diet quality groups having 41% and 36% lower risk of increasing disability respectively, and 0.30 P-MSSS points less disability progression. Higher diet quality was not associated with fatigue or depression risk over time. Meat-eating was associated with a 0.22 P-MSSS points higher disability at baseline, while prospectively, meat consumption was associated with 76% higher risk of increasing disability and 0.18 P-MSSS points higher disability progression. Dairy consumption showed mixed associations at both the beginning of the study and over the follow-up period.
Understanding the results
These results are reassuringly broadly in keeping with those of the large-scale U.S. based NARCOMS Study, published in 2017, that showed those with the highest diet quality scores had lower levels of disability, less depression, lower pain scores and less cognitive impairment.
It is important to note the limitations of any study, and indeed there were some in this case.
Firstly, the data was self-reported, and while this is prone to recall bias, patient-reported measures are now widely used in assessing clinical outcomes, and the assessment tools used have previously been validated for this purpose.
As recruitment for HOLISM was done through websites promoting healthy lifestyles in MS (like our own), there is of course the chance of participation bias. Those most likely to complete the follow-up period tended to have higher levels of education, employment, less clinical severity, and a tendency towards healthy lifestyle behaviours. However, the significant dietary results persisted once these factors had been allowed for and analysed using a variety of statistical methods, reassuring us as to the accuracy of the findings.
It would also have been preferrable to record the dietary data on a prospective basis, rather than by recall, although this would have likely increased attrition rates due to the burden of data recording put on the participants. The DHQ was not designed to specifically assess MS patients, but rather was intended for a cardiac population. The questionnaire also did not capture enough data on dairy and meat consumption to give the greatest odds of achieving a statistically significant result. But neither was it specifically intended for this purpose.
Finally, there is the potential that those people with greater clinical severity or healthier lifestyle behaviours may report their outcomes differently from one other, known as differential information bias.
Nevertheless, it is very likely that these results are applicable to the general MS population, given that the clinical and demographic characteristics of the study cohort are closely matched, as well as the fact that HOLISM includes participants from countries with some of the highest rates of MS.
Sticking with OMS
Overall, these results indicate a clear beneficial relationship between better quality of diet, possibly including reduced meat consumption, and less disability progression. While there was no prospective association between diet and fatigue, there was some evidence that improved diet scores were associated with a decreased risk of depression over time.
Collectively, the consistency of the results in this and other studies, the dose-dependent relationships, and the underlying biological mechanisms demonstrate substantial evidence for a link between quality of the diet and disability in people with MS. If further studies confirm these results, this could and should inform clinicians and those people living with MS as to the lifestyle interventions that reduce disease progression.
In the meantime, I won’t need a randomised controlled trial to prove the benefits of wearing a parachute should I jump out of an aeroplane, and I think I might just stick with OMS too!
Simpson-Yap S, Nag N, Probst Y, Jelinek G, Neate S. Higher-quality diet and non-consumption of meat are associated with less self-determined disability progression in people with multiple sclerosis: A longitudinal cohort study. Eur J Neurol. 2021 Aug 14. doi: 10.1111/ene.15066. Epub ahead of print. PMID: 34390078.
Fitzgerald KC, Tyry T, Salter A, Cofield SS, Cutter G, Fox R, Marrie RA. Diet quality is associated with disability and symptom severity in multiple sclerosis. Neurology. 2018 Jan 2;90(1):e1-e11. doi: 10.1212/WNL.0000000000004768. Epub 2017 Dec 6. PMID: 29212827.